The present invention relates to heat releasing devices, and more particularly to devices for releasing heat from heat emitting elements, such as transistors, thyristors and like semiconductor elements, attached thereto.
The term "aluminum" as used herein and in the claims includes pure aluminum, commercial aluminum containing small amounts of impurities and aluminum alloys.
Heat releasing devices of the type mentioned are generally those including fins and made entirely of extruded aluminum. To assure specified strength of the die, however, there are limitations on the height of the fins and also on the spacing between the fins in view of the extrusion orifice. Accordingly if a group of fins are adapted to provide the desired effective heat releasing area, the device becomes large-sized. Extrusion techniques further involve limitations on the thickness of fins, consequently rendering the heat releasing device heavier. In addition, heat releasing devices made of extruded material are limited in heat releasing efficiency, so that a larger number of such devices must be used for releasing heat from an increased number of heat emitting elements, giving rise to the necessity of using longer lead wires for the heat emitting elements. In the case of acoustic systems, this is likely to produce a distorted sound or noises. It is therefore desired to provide heat releasing devices which are small-sized, lightweight and efficient.